Enhanced sensitivity in graphene-based SPR biosensors using electrical bias.

A theoretical framework to increase the sensitivity of graphene-based surface plasmon resonance (SPR) biosensors by the application of electrical bias voltage across the sensor surface is presented. Graphene layers deposited on thin gold film (50 nm) form the sensor surface system where the surface plasmon is excited. The real and imaginary parts of the refractive index of this gold-graphene system can be controlled by tuning its chemical potential using electrical modulation.

The effect of visual perturbation upon femoral acceleration during the single and bilateral squat.

Objectives: Record femoral accelerations using a smartphone accelerometer attached to the distal thigh during single-legged (SLS) and bilateral squats, and each squat condition occurred under two visual conditions: 1) normal vision and 2) visual perturbation with stroboscopic glasses.

Design: Repeated-measures cross-over with counter-balanced order for four total conditions.

Setting: Laboratory.

Radio-frequency clock delivery via free-space frequency comb transmission.

We characterize the instability of an rf clock signal caused by free-space transmission of a frequency comb (FC) under typical laboratory conditions. The phase-noise spectra show the involvement of multiple random processes. For a 10 m transmission, the rms timing jitter integrated over 1-10(5) Hz is 95 fs, and the root Allan variance over 1 s is 4x10(-13).